Unilateral flail chest is seldom a lethal injury.

BACKGROUND: The chest cage is a common target for traumatic damage. Although relatively rare, it is considered to be a serious condition with significant reported mortalities. As most flail injuries are accompanied by severe extrathoracic injuries, it is often difficult to pinpoint a single injury responsible for the patient's death. AIM: To investigate the factors related to mortality when flail injury is diagnosed. METHODS: Data from the Israel National Trauma Registry between 1998 and 2003 included 11,966 chest injuries (262 flail chest injuries) out of a total of 118,211 trauma hospitalisations. Mortality figures were analysed to determine which factors, singly or in combination, influenced flail chest mortality. RESULTS: Road crashes accounted for most flail injuries (76%). The total mortality was 54 (20.6%) of 262 patients with flail chest injuries. 13 (20.4%) of the deaths occurred soon after admission to the emergency room and 37 (68.5%) within the first 24 h. Mortality in moderate to severe injuries (injury severity score (ISS) 9-24) was 3.6% and that in critical injuries 28.5% (ISS >24). Mortality increased with age: 17% in those aged <45 years, 22.1% in those between 45 and 64 years and 28.8% in those >65 years. Age remained a risk for inpatient death when adjusted for severity. Mortality in isolated unilateral flail injury was not more than 6%. Total mortality for traumatic brain injury (TBI) and flail was 34%. Flail, TBI and other major injuries increased the mortality to 61.1%. CONCLUSIONS: Advanced age is associated with higher mortality. Isolated unilateral bony cage instability infrequently leads to death in patients who make it to the emergency department but rather its combination with additional extrathoracic trauma.

Sorin Bicarbon bileaflet valve: a 10-year experience.

OBJECTIVE: To present a large 10 year experience of a collaborative evaluation of the Sorin Bicarbon (SB) mechanical prosthesis carried out in 14 centers in eight Western European countries. METHODS: Between 4/90 and 12/96, 2078 SB valves were implanted in 1875 patients aged 4-84 years (mean 58), 1108 males and 767 females. The valves inserted were 1026 aortic valve replacement (AVR), 656 mitral valve replacement (MVR) and 203 double valve replacement (DVR), additional procedures performed in 467 patients (282 coronary artery bypass grafting). RESULTS: Early mortality was 97 (5%), overall survival at 8 years was 71.8% AVR, 69.4% MVR, 81.4% DVR. Total late valve-related deaths were 55; overall freedom from valve-related death at 8 years was 95%. New York Heart Association (NYHA) status after surgery: 78% improved and 17% unchanged. Twenty-two valve thrombosis were observed, one fatal; overall freedom from thrombosis at 8 years was 98.5%. Embolism occurred in 95 patients, 77 cerebral events (16 deaths), overall freedom from embolism was 90.7% at 8 years. Six hemolytic events and 26 non-structural dysfunction (all periprosthetic leaks) were reported. Major bleeding occurred in 66, with mortality rate of 32% mainly when intracerebral. Overall freedom from bleeding was 90.8% at 8 years. Endocarditis occurred in 31 patients, 29% were fatal; overall freedom from endocarditis was 97.8% at 8 years. Reoperation was performed in 49 cases--periprosthetic leak 20, infective endocarditis 14, thrombosed valve 13 (and non-valve related-2). Mortality (early and late) occurred in three reoperated patients. CONCLUSIONS: This is a durable and effective mechanical valve substitute with low morbidity and mortality and good functional results.

Nicorandil decreases postischemic actin oxidation.

This study examined the hypothesis that preconditioning can decrease postischemic oxidative protein damage. Isolated rat hearts were subjected to 25 min of normothermic global ischemia followed by 45 min of reperfusion. These were compared with hearts pretreated with 20 microM nicorandil or preconditioned with two cycles of ischemia. Changes in the high energy phosphates, ATP and phosphocreatine, were followed using (31)P-NMR spectroscopy. Protein carbonyls were assessed using an immunoblot technique. Postischemic hemodynamic function and high energy phosphates recovered to significantly (p <.05) higher levels in nicorandil-treated and ischemic preconditioned hearts as compared to controls. Postischemic protein carbonyl formation was highest in control reperfused hearts but reduced to intermediate between control and preischemic hearts by ischemic preconditioning and virtually prevented by nicorandil pretreatment, with a prominent band at 43 kDa significantly affected (p <.05). Based on immunoshift and immunoprecipitation studies, this band was identified as a mixture of actin isoforms. These studies support the conclusion that nicorandil diminishes protein oxidative damage in general, and specifically actin oxidation, which in the presence of improved supply of high energy phosphates, leads to enhanced postischemic contractile function.

Novel synthetic selectively degradable vascular prostheses: a preliminary implantation study.

BACKGROUND: Vascular grafts perform less well than autologous arterial or vein grafts. The purpose of this study was to evaluate the short-term performance of selectively biodegradable filament-wound vascular prostheses, comprising elastomeric poly(ether urethane) (Lycra) scaffolds and flexible, hydrophilic biodegradable coatings. MATERIALS AND METHODS: Two types of selectively biodegradable vascular grafts were manufactured, comprising a filament-wound Lycra scaffold, subsequently coated with a biodegradable poly(ethylene glycol)/poly(lactic acid) (PELA) block copolymer. The two types of grafts differed in both the overall porosity of the scaffold and the hydrophilicity of the biodegradable constituent. A 60-mm-long and 6-mm-diameter filament-wound and polytetrafluoroethylene (ePTFE) grafts were implanted as interposition prostheses, randomly, at the right- and left-side carotid arteries. RESULTS: Implantation studies proved the grafts to be patent and pulsatile for periods of up to 3 months. Increasing the scaffold porosity and enhancing the hydrophilicity of the biodegradable component improved both the transmural tissue ingrowth process and the vascularization of the prosthesis wall. Also, a well-adhered peripheral tissue and a thin, uniform intima and endothelial lining were obtained. All ePTFE graft controls, although patent, were rather stiff and nonpulsatile. A thick pseudointima, poorly attached to the prosthesis inner surface, was observed. The compliance of the wet grafts was significantly higher than in the dry state, stemming mainly from the water-plasticizing effect on the biodegradable component. The grafts explanted after a period of 6 weeks exhibited compliance only slightly lower than that of the wet grafts. After 12 weeks, however, the hoop compliance was 20% lower than that prior to implantation. At 100 mm Hg, for example, the original compliance of the wet graft was 2.5%/100 mm Hg decreasing to 2.0%/100 mm Hg after a 3-month implantation. The compliance reduction with implantation is attributed to the ingrowth of the perigraft tissue as revealed by the histological study. A compliance of 2.0%/100 mm Hg is slightly better than that of a standard PTFE graft with an original compliance of 1.6%/100 mm Hg. Yet it is still an order of magnitude smaller than that of a canine carotid artery. CONCLUSIONS: The improved mechanical properties and enhanced healing of the highly porous filament-wound Lycra scaffold graft coated with hydrophilic biodegradable PELA has the potential of being a highly effective small caliber prosthetic graft.

Bicarbon valve -- European multicenter clinical evaluation.

OBJECTIVE: Fifteen collaborating centers in eight countries present their pooled experience with the new Bicarbon bileaflet valve. METHODS: Between 4/90 and 4/96, 1351 patients, 806 males and 545 females, aged 10 to 83, mean 58.4 +/- 12.4, underwent valve implantation. OPERATIONS: aortic valve replacement (AVR), 726; mitral valve replacement (MVR), 475; double valve replacement (DVR), 150. Additional procedures: CABG, 211; TV repair, 64; other, 152. RESULTS: Mortality: 67 early (seven valve related) and 56 late (40 valve related). Valve thrombosis: six obstructive, three non-obstructive; embolism: nine major cerebral, 37 other. Major bleeding: 29. Hemolysis: two clinically significant. Non-structural dysfunction: 24 paravalvular leaks, one leaflet interference. No structural failure! Endocarditis: 24. Reoperation 48: 22 non-structural dysfunctions, 14 endocarditis, seven thrombosis and embolism, five other. Estimated 5-year freedom from valve-related deaths is 97.2% for AVR and 92.4% for MVR; 4-year freedom from valve related deaths for DVR is 90.5%. Mean calculated NYHA improvement is 1.24. CONCLUSIONS: The Bicarbon mechanical prosthesis is well designed, durable, has good hemodynamic features and an acceptably low incidence of complications.

Cardioprotective effect of L-arginine in myocardial ischemia and reperfusion in an isolated working rat heart model.

BACKGROUND: Studies in myocardial ischemia and reperfusion have demonstrated damage to endothelium, impaired production and release of vasoactive substances such as nitric oxide, and marked alteration in endothelium-dependent relaxatin of the coronary vasculature. This study was designed to examine the cardioprotective effect of exogenous administration of L-arginine, a precursor of nitric oxide, during ischemia and reperfusion, particularly using oxygenated crystalloid cardioplegia. METHODS: Seventy energy-depleted isolated working rat hearts were arrested by cardioplegia and subjected to 60 min normothermic global ischemia followed by 10 min nonworking and 30 min working reperfusion (Gr 1). L-arginine (3mM or 10mM) was added to the cardioplegic solution (Gr 2,3 respectively), reperfusion (Gr 6,7 respectively), throughout the experiment (Gr 4,5 respectively), and with Nw-nitro-L-arginine methyl ester (L-NAME), a competitive inhibitor of nitric oxide synthase (Gr 8). RESULTS: At 30 min of working heart reperfusion, compared to control all arginine containing groups (Gr 2-7) exhibited a significant improved recovery of cardiac output (64.7+/-21.2, 98.1+/-21.1, 90.9+/-11.7, 88.9+/-16.2, 83.1+/-7.4, and 90.8+/-10.6, mean +/- SD% Gr 2 to 7 respectively, vs Gr 1 36.3+/-20%, p<0.01). Significant recovery improvement was observed also in other hemodynamic parameters (coronary flow, aortic peak pressure), as well as biochemical recovery assessed by O2 consumption ratio, release of lactic dehydrogenase at reperfusion and regeneration of ATP. The L-NAME group had a significant poorer hemodynamic and biochemical recovery. L-arginine had no effect on the preischemic hemodynamic parameters. CONCLUSIONS: These results support the cumulative data considering L-arginine as a cardioprotective agent in postischemic reperfusion injury.

The Sorin Bicarbon valve: clinical evaluation in Israel.

BACKGROUND: Four collaborating centers pooled their results with the Sorin Bicarbon Bileaflet valve. MATERIAL AND METHODS: Between 6/91 and 11/95, 431 patients, 235 males and 196 females, underwent valve replacement using the new Sorin prosthesis; age range: 16-88, mean 61.4 yrs. OPERATIONS: AVR - 206, MVR - 177, TVR - 1, DVR - 47. Additional procedures - 139: CAB -117, valve repair - 22. AV sizes: 19-27, MV sizes: 21-33. RESULTS: Thirty day mortality was 4.3%. Early complications included: CVA - 1.4%, +ve blood culture - 2%, reop for bleeding - 5%. Late complications: infective endocarditis - 2.3%, valve thrombosis - 0.2%, thromboemboli - 2.5%, major bleeding - 1.6%, reoperation - 3%, late deaths (all causes) - 4.3%. No structural deterioration has been reported with this valve and acceptable gradients have been observed. Hemolysis is negligible. CONCLUSIONS: Based on this intermediate experience the Sorin Bicarbon prosthesis is well-designed with good hemodynamic properties, and an acceptably low incidence of complications.

New solution for prolonged myocardial preservation for transplantation.

BACKGROUND: A solution for prolonged cold storage of the heart has been developed. The Jerusalem-Cape Town Solution (JCT) is an "intracellular" type cardioplegic solution and is formulated to (1) minimize hypothermic-induced cell swelling, (2) diminish intracellular acidosis, (3) prevent the expansion of the interstitial space during the reperfusion, (4) protect against oxygen free radical injury during early reperfusion, and (5) provide substrates for regenerating high-energy phosphates. METHODS: With a Langendorff model, rat hearts were subjected to 15 minutes of perfusion with Krebs-Henseleit, 10 minutes of cardioplegic infusion and 20 hours of cold storage (5 degrees to 6 degrees C). Hearts were reperfused for 60 minutes and hemodynamic recovery was assessed. The hearts were assigned to three groups (eight hearts in each), according to the cardioplegic solution used: group 1, JCT; group 2, Bretschneider's HTK cardioplegic solution; and group 3 University of Wisconsin cold storage solution. RESULTS: After 60 minutes of reperfusion, the recovery of the coronary artery flow in group 1 (JCT) was significantly better than in group 2, and slightly better than in group 3 (64% +/- 8.9%, 47.2% +/- 11.6%, 52.5% +/- 19.9%, mean +/- SD, respectively; group 1 versus group 2, p < 0.01). The recovery of the left ventricular developed pressure (LVDP) was significantly better in group 1 compared with group 2 and group 3 (60.2% +/- 14.5%, 41.1% +/- 12.6% and 36.5% +/- 10.1%, respectively; p < 0.01). The recovery of the heart contractility expressed by the product of LVDP and the heart rate (LVDP x heart rate) was significantly higher in group 1 than in group 2 and group 3 (47.5% +/- 3.4%, 23.6% +/- 9.6%, and 28.7% +/- 8.3%, respectively, p < 0.001). In hearts stored for 12 hours in JCT or HTK, the recovery of the heart contractility did not differ significantly (73.4% +/- 12.7% or 70.8% +/- 30.8%, respectively). Modified reperfusion aimed to improve postischemic heart recovery did not bring significant changes in cardiac mechanical function but resulted in an increase in postischemic coronary artery flow recovery in hearts reperfused with amino acid-enriched buffer. CONCLUSIONS: The JCT solution is effective (as well as HTK) in preserving the ischemic hearts for up to 12 hours. It is superior to HTK or University of Wisconsin solution at 20 hours of isolated ischemic storage.

Estrogen induces nitric oxide-mediated vasodilation of human mammary arteries in vitro.

Human internal mammary arteries (IMA) are relatively protected from atherosclerosis. Estrogen plays a protective role in cardiovascular disease. It causes in vitro and in vivo vasodilatation, but the mechanisms are contradictory. To investigate the in vitro vasomotor effect of estrogen on IMA and the role of endothelium, we studied 30 IMA segments harvested from 10 men during coronary artery bypass grafting surgery. Patients with diabetes mellitus, hypercholesterolemia, hypertension, and smoking were excluded. Twenty IMA rings had intact endothelium ((+)Endo) and 10 rings were denuded of endothelium ((-)Endo). Vasomotor response of each ring was expressed as the percentage of maximal response to norepinephrine (NE). Acetylcholine (10(-8)-10(-5) M) given to (+)Endo and (-)Endo rings induced vasorelaxation of 72 +/- 30.4% and vasoconstriction of 48.5 +/- 20.1%, respectively. 17-Beta-estradiol (10(-8)-10(-5) M) given after maximal precontraction with NE induced marked relaxation in (+)Endo (80.9 +/- 39.2%), but no significant vasomotor effect in (-)Endo rings (P < 0.0001). Vasorelaxation to 17-beta-estradiol (10(-6) M) in (+)Endo rings was 64.5 +/- 18.4 and 8.6 +/- 8.4%, before and after 15-min treatment with nitric oxide synthase inhibitor, L-nitroarginine methyl ester, respectively (n = 14, P < 0.0001). Tamoxifen (10(-6) M) decreased 17-beta-estradiol (10(-7) M)-induced relaxation by 71%. In conclusion, 17-beta-estradiol induces endothelium-dependent NO-mediated vasodilation of human mammary arteries in vitro. This response is mediated through estrogen receptors.

Naturally produced extracellular matrix is an excellent substrate for canine endothelial cell proliferation and resistance to shear stress on PTFE vascular grafts.

PURPOSE: Successful development of a vascular prosthesis lined with endothelial cells (EC) may depend on the ability of the attached cells to resist shear forces after implantation. The present study was designed to investigate EC detachment from extracellular matrix (ECM) precoated vascular prostheses, caused by shear stress in vitro and to test the performance of these grafts in vivo. METHODS: Bovine aortic endothelial cells were seeded inside untreated polytetrafluoro-ethylene (PTFE) vascular graft (10 x 0.6 cm), PTFE graft precoated with fibronectin (FN), or PTFE precoated with FN and a naturally produced ECM (10(6) cells/graft). Sixteen hours after seeding the medium was replaced and unattached cells counted. The strength of endothelial cell attachment was evaluated by subjecting the grafts to a physiologic shear stress of 15 dynes/cm2 for 1 h. The detached cells were collected and quantitated. PTFE or EC preseeded ECM coated grafts were implanted in the common carotid arteries of dogs. RESULTS: While little or no differences were found in the extent of endothelial cell attachment to the various grafts (79%, 87% and 94% of the cells attached to PTFE, FN precoated PTFE, or FN+ECM precoated PTFE, respectively), the number of cells retained after a shear stress was significantly increased on ECM coated PTFE (20%, 54% and 85% on PTFE, FN coated PTFE, and FN+ECM coated PTFE, respectively, p <0.01). Implantation experiments in dogs revealed a significant increase in EC coverage and a reduced incidence of thrombus formation on ECM coated grafts that were seeded with autologous saphenous vein endothelial cells prior to implantation. CONCLUSION: ECM coating significantly increased the strength of endothelial cell attachment to vascular prostheses subjected to shear stress. The presence of adhesive macromolecules and potent endothelial cell growth promoting factors may render the ECM a promising substrate for vascular prostheses.

Early experience with the Sorin bileaflet prosthetic valve.

Between 1.6.1991 and 31.5.1995, 62 patients underwent heart valve replacement with Sorin Bicarbon bileaflet prosthetic valve, age 16-83 years (mean 60.5). The valve disease was rheumatic in 37 cases, degenerative in 17, congenital in 4 and miscellaneous etiologies in the other 4. The valve lesion was AS in 24 patients, AR in 5, AR+MS in 2, MS in 13, MR+MS in 6, MR in 6, tricuspid prosthetic stenosis in 1, A+M disease in 3, and a clotted prosthetic valve (Sorin disc) in 1. CAD was present in 14 patients (23%) and AF in 19 (31%). 11 had moderate pulmonary hypertension and 4 severe. Preoperatively 6 patients were in FC II, 40 in FC III and 16 in FC IV. Operative procedures included AVR 18, AVR+CABG 13, AVR+T annuloplasty 1, AVR and open M valvotomy 1, MVR 7, MVR+T annuloplasty 7, MVR+AVR (Medtronic) 1, MVR+AVR 1, TVR, prosthetic valve replacement 1, and MVR+CABG 1. Hospital mortality was 3 (4.8%) -- one due to ruptured A-V groove and two due to LoCO. Postoperative complications: LoCO necessitating IABP -- 3 patient; 3 transient CVA and 1 CVA with hemiplegia. One patient had aortic prosthetic valve endocarditis 18 months following the operation necessitating reoperation. Other cases were treated for positive blood cultures. One patient had CVA after anticoagulant were discontinued. 28 patients are in FC I, 22 in H, 4 in III and 1 in IV. 4 patients are lost to follow-up. These data suggest that the Sorin Bicarbon Prosthetic valve can be safely and effectively used for heart valve replacement.

A 31P NMR study of preconditioned isolated perfused rat heart exposed to intermittent ischemia.

Exposure to a short ischemic period (ischemic preconditioning, IP) will protect the heart from damage following a subsequent longer ischemic episode. The aim of the study was to test whether IP is cardioprotective in the setting of repeated ischemia-reperfusion cycles. Thus, Langendorff-perfused hearts, exposed to IP, were subjected to three consecutive ischemia-reperfusion (10/15 min) cycles. Myocardial energetics, manifested by 31P NMR spectroscopy, was correlated with hemodynamics. ATP recovery was significantly higher for the IP group compared with control (P < 0.02) during reperfusions. However, there was no significant difference in ATP recovery during the three ischemic intervals. The supernormal recovery of phosphocreatine recorded during reperfusion was lower for the IP group (approximately 120%) compared with control (approximately 135%, P < 0.065). Better recovery of the left ventricular-developed pressure was noted during reperfusions for the IP group and became significant only during the last reperfusion (86% versus 68%, P < 0.025). In conclusion, the above results support prolonged IP cardioprotection.

Acute effect of thyroid hormone in the rat heart: role of calcium.

Several observations provide some clues as to the possible mode of the regulatory action of thyroid hormone (TH) in the heart, indicating delayed action at the level of the nucleus and acute effects on the plasma membrane. Here we present evidence for a direct and rapid stimulatory effect of TH in the intact normal heart. In the isolated perfused rat heart, 3,5,3'-tri-iodothyronine (T3) produced a positive inotropic effect increasing both the left ventricular peak systolic pressure (P) and +dP/dt values, but had no significant effect on heart rate. This effect of T3 was: (1) very rapid in onset (starting after 15 s) and transient, increasing gradually to reach a maximum (80% above control) at about 20 min, and declining progressively 20 to 30 min later; (2) dose-related and biphasic, occurring at physiological concentrations as low as 1 pM (+dP/dt) and 10 pM (P), reaching a maximum at 1 nM, and decreasing at higher concentrations; and (3) thyroid hormone specific, as shown by the effects of several TH analogs (L-T3 > L-thyroxine (T4) = D-T3 > D-T4; 3,3',5'-tri-iodothyronine (rT3), 3,5,-L-di-iodothyronine and DL-thyronine had no effect). The calcium blockers nifedipine and verapamil, at concentrations of 10(-8) - 10(-5) M given before or after the addition of T3 (10(-9) - 10(-6) M), inhibited the T3-induced increase in cardiac inotropic activity in a time- and dose-related fashion. We suggest that the acute effect of TH in the heart is plasma membrane-mediated and calcium-dependent.

Luke warm blood cardioplegia for CAB surgery in patients with severely impaired LV function. Improved results.

Ward blood cardioplegia (WBC) has recently been reported to improve myocardial protection in adult open heart surgery, especially in high risk cases. However, WBC has been reported to have some disadvantages including narrow safety margins concerning brain and kidney perfusion. We therefore modified our technique to utilize luke-warm blood cardioplegia (LWBC). We carried out 470 open heart procedures using luke-warm cardioplegia (anterograde + retrograde perfusion) from 1/2/1991 - 30/9/1992; 94 had LVEF < 30% and form the basis of this study. Other major risk factors in this group included: > 70 yrs - 26 patients, L main > 50% - 14 patients, emergencies - 11 patients, redo's - 3 patients. Eightyone patients underwent CAB only; 3 had additional MVR, 3 additional closure acute VSD of whom one underwent additional LV aneurysmectomy, one additional AVR; 4 patients underwent AVR only, and 2 MVR. Average number of grafts/patient for the 81 isolated CAB's was 4.5. IABP was necessary postbypass in 4 patients (9 emergencies were on IABP support at time of operation). Thirty day mortality was 3 patients (3.2%). Late mortality was 5 cases. These results are superior to those achieved using cold protection and warm blood cardioplegia. LWBC is a safe method for myocardial protection in patients undergoing CAB, particularly when LV function is severely compromised.

Myocardial protection by warm blood cardioplegia. A 31P nuclear magnetic resonance spectroscopy study of an isolated perfused rat heart.

OBJECTIVE: A study of the protective efficiency imparted by intermittent warm blood cardioplegia (WBCP) using perfused rat heart model. METHODS: Hemodynamic parameters were monitored simultaneously with metabolic changes in high-energy phosphates using 31P-NMR spectroscopy. Following 30 min perfusion with Krebs-Henseleit (KH) buffer, all hearts were arrested for one hour (G1 and G2) and than reperfused with KH for 30 minutes. A warm oxygenated crystalloid cardioplegia (WCCP, modified St Thomas' hospital solution) was used for the control group (G1). The second group of hearts (G2) were arrested with oxygenated WBCP (K+ = 15 mM; Hct = 15-20%) and the third group (G3), was subjected to a protocol consisting of 4 periods (10 min each) of WBCP interspersed by 10 min of global ischaemia. RESULTS: The post-arrest percentage recoveries of LVDP, +dP/dt and HR were respectively: 88, 93 and 90 for G1 (n = 8); 97, 100 and 98 for G2 (n = 10); 76, 79 and 91 for G3 (n = 12). The corresponding metabolic recoveries of ATP and PCr were respectively, 85 and 90 for G1; 91 and 98 for G2 and 73 and 85 for G3. The PCr level declined during the arrest period in G1 contrasting with elevated PCr level (> 140%) during the WBCP arrest in G2. After an initial rise to approximately 140%, PCr level gradually decreased during the intermittent WBCP interval (G3). CONCLUSIONS: At normothermia, with equal CF rates, continuous WBCP provides better myocardial protection, through an effective oxygen supply, compared with WCCP. During the intermittent periods of ischaemia, certain metabolic and hemodynamic dysfunction occurs.

Value of dobutamine/nitrate radionuclide angiography in predicting revascularization effects on ventricular function.

OBJECTIVE: Dobutamine and Nitrate Radionuclide Angiography (RNA) may help to distinguish viable from nonviable myocardium and to predict revascularization effects on LV function. SETTING: Ambulatory. EXPERIMENTAL DESIGN: Prospective. PATIENTS AND METHODS: We studied 12 patients (11 male, 1 female; mean age 56 +/- 10 years) with three-vessel disease, severe LV dysfunction, and prior MI for a mean follow-up time of 10 +/- 3.4 months. Thallium-201 scintigraphy favored potential viability in all patients: inducible ischemia with satisfactory perfusion in more than one coronary arterial territory. Global and regional LVEF's were calculated from preoperative RNA (baseline rest study and with continuous dobutamine infusion with gradual rate increase plus oral nitrates) and postoperative RNA at 1 and 6 months. RESULTS: There was no operative mortality, but two late deaths occurred. Symptomatically, most patients showed improvement. Global LVEF increased during dobutamine and nitrates preoperatively (p < 0.01), but not at 1 and 6 months postoperatively (without pharmacological intervention). Mean LVED volume was not significantly changed postoperatively. Regional EF improvement was found in 4 out of 9 LV wall segments under dobutamine and nitrates, and this increase persisted postoperatively at 1 and 6 months. CONCLUSIONS: Mild but significant increase in global LVEF during dobutamine and nitrates administration is not predictive of postoperative LVEF improvement. However, regional EF improvement appears to be predictive of post-revascularization LV functional improvement.

New experimental technique to study blood cardioplegia in the isolated, perfused rat heart.

Blood cardioplegia has been extensively studied clinically and in the large animal experimental model. We describe here a modification of the original Langendorff technique to study continuous warm blood cardioplegia in the isolated, perfused rat heart. The excised heart is mounted on the perfusion apparatus and perfused with Krebs-Henseleit buffer. Prearrest hemodynamics are recorded. The shed blood in the mediastinal cavity (8 to 12 mL) is collected, filtered, and reconstituted into cardioplegic solution (hematocrit, 0.20; K+, 15 mmol/L). Hearts are arrested and maintained at 37 degrees C by continuous recirculation of blood cardioplegia for 1 hour. The blood cardioplegia system consists of a Silastic tubing oxygenator, peristaltic pump, and two filters (40 microns pore size). The heart is reperfused with Krebs-Henseleit solution, and postarrest hemodynamics are recorded. Percentage recovery of peak left ventricular pressure, heart rate, and coronary flow were 98.5 +/- 3.1, 102 +/- 4.2, and 98.5 +/- 4.5 (mean +/- standard error of the mean; n = 6), respectively. Myocardial oxygen consumption during arrest was 57 microL.min-1.g-1 dry wt, which is 10% of the myocardial oxygen consumption of a beating heart in in-vivo and ex-vivo models. These results suggest the feasibility of studying blood cardioplegia in the isolated, perfused rat heart model under controlled conditions. Continuous warm blood cardioplegic arrest provided excellent myocardial protection for 1 hour in this model.